Rotary pump



. March 7, 1939. R. bEMING "2,149,337

' ROTARY PUMP Filed Dec. 11, 1954 2 Sheets-Sheet 1 v INVENTOR I RobertDemin F17. 5 t Y v .7 W Mafia ATTORNEYS March 7, 1939.

R DEMING ROTARY PUMP Filed Dec. 11, 19:54

2 Sheets-Sheet 2 Robe BY kWcCumvl-i OR Demi n ATTORNEY 6 Patented Mar.7, 1939 I ROTARY PUMP 1mm Deming, Norwood, Ohio, assignor to Dem- I ing.Rotary Pump -Company,'Cincinnati, Ohio a corporation of Ohio ApplicationDecember 11, 1934, Serial No. 756,989

12 Claims. (01. 103-436) This invention relates to fluid pressure orvacv uum pumps of the rotary piston type and has for its object toprovide a pump in which the leakage of the fluid being pumped pastrelatively moving parts of the pump is reduced to a minimum, and inwhich the pressure in the high pressure side of the pump chamber isutilized to maintain a fluid-tight engagement between the vanes whichact as pistons .or sea-ling members and the relatively movable partswith which the engage, so as to reduce leakage past such pistons orsealing members from the high pressure side to the low pressure sideofthe pump chamber. A further object of the invention is to'provide apump in which the relatively movable parts are provided with sealinggrooves so disposed as to effectively check flow of the fluid beingpumped between the relatively'movable contacting surfaces of the pumpelements.

[ A further object is to so conduct, apply and utilize the normal forcesgenerated by the pump- .ing operation as to make the sealing provisionsmore effective.

With the'above. andother objects in view, the

A; invention may be said to comprise the pump as illustrated in theaccompanying drawings hereinafter described and particularly-set forthin the appended claims, together with such variations.

and modifications thereof as will'be apparent to one'skilled in the artto which] the invention appertains.

Reference should be had to the accompanying drawings forminga part ofthis specification,

in which:

Figure 1 is a transverse section through a ro-,

tary pump embodying the invention,- a section being taken at rightangles to the axis of the pump and through the body of the rotor;

Fig. 2 is a perspective view of the body portion of a pump vane;

- Fig. 3 is a perspective view of a sealing shoe with a convex workingface for engagement interiorly with a cylindrical surface;

Fig. 4 is a perspective view of a sealing shoe witha concave workingface for engagement exteriorly with a cylindrical surface;

Fig. 5 is a diagrammatic view showing the pressures exerted upon theshoes;

.Fig. 6 is a diagrammatic view showing the pressures exerted upon thevane;

. Fig. 'l is a sectional view showing a pump with a one-piece vane:

Fig. Bis a perspective view of theone-piece' vane shownin Fig. 7; I

Fig. 9 is a diagrammatic view showing the effect the axis of rotation,;are referred -to as end of centrifugal force on a'vane disposed at anangle to the radius;

Fig. 10 is a view similar to Fig. 9 showing the vane oppositelyinclined; and

Fig. 11 is a sectional view showing a multivane 5 pump embodying theinvention.

An important feature of the present invention is the provision of anefiective seal between relatively sliding parts of a rotary pump such asa sliding vane or an oscillatable shoe, and the parts 10 with which thevane or shoe has sliding contact. In the following description, it is tobe understood that by working face of a vane or shoe, is meant that faceof the vane or shoe which engages with a part of the pump which is rela-15 tively rotatable with respect to the part which carries the vane orshoe. The faces of the shoe or vane perpendicular to faces.

The faces of the vane or shoe opposite the working face, are referred toas "bottom faces".

The side of the shoe or vane disposed transversely to the direction of.rotation-and which receives the initial pressure from the fluid beingpumped, is referred to as "the high pressure side or face, and thecorresponding side of. the recess in which the shoe or vane is mountedis referred to as the high pressure side or face. The face of a shoe orrecess opposite the high pressure side 30 or face is referred to as thelow pressure face or side. Grooves, channels, recesses, or spacesprovided for the purpose of applying and directing pressures forces aresometimes referred to herein as pressure pockets. v 35 'In Figure 1 ofthe drawings, there is shown a pump housing I enclosing a cylindricalchamber in which there is mounted a rotor 2, the axis 3 of which isdisposed eccentrically with respect to the cylindrical housing, therotor 2 being of 40 cylindrical form and of smaller diameter than thechamber in which it is mounted. The rotor is positioned withitsperiphery in contact with the chamber wall along a longitudinal tangentline to provide a seal between the inlet and outlet 45 ports. 'The rotorhas a longitudinal slot 4 in which is slidably'mounted the body portion5 of a sealing vane, the working face of which is provided with anoscillatable shoe 6 having an arcuate convex bottom or seating face Iwhich fits 50 in an arcuate recess in the body portion 5.

The shoe I has'a convex working. face- 8, the radius ofwhich*corresponds to that ofthe cy lindrical chamber, and which contactswith the wall of the cylindrical chamber. ,I'he bottom I or seating faceI of the shoe 6 is of shorter radius than the working face 8 andintersects the working face at'opposite sides of the shoe.

During operation of. the pump the vane consisting of the slidable bodyportion 5 and oscillatable shoe 6 is pressed outwardly towards thecylindrical wall of the pump chamber, to maintain the working face 8 ofthe shoe incontact throughout its width and lengthwith the cylindricalwall of the chamber.

fluid from the inlet to the outlet of the pump.

In order to provide a more eifective seal between-the rotor and thechamber wall along the line of contact between the rotor and wall, anoscillatable shoe 9 is mounted in a recess in the housing and this shoehas an arcuate convex bottom or seating face ill which fits in an arcuate recess in the housing wall, and anarcuate concave working face H ofthe same radius as the rotor which bears against the surface of therotor. The bottom or seating face in is a shorter radius than theworking face ii and intersects the working face at opposite sides of theshoe.

'The shoe 9 maintains contactvwith the rotor to provide a moreeife'ctive seal between the inlet and outlet.

As shown in Fig. 2 of the drawings, the body portion of the vane hasparallel longitudinal grooves i2 on its low pressure faceand'longitudinal channels it on the high pressure, face thereof. On thehigh pressure side there is at least one passage i5'which opens at oneend to the shoe seating recess and at its opposite end to the bottom ofthe vane. The passage I5 is intersected by the channels 14 which providepressure pockets along the high pressure face of the vane for fluidunder pressure which acts to press the vane toward the low pressurewallv of its recess or slot so that the sealing grooves l2 are effectiveto prevent leakage of fluid from the bottom of the recess through thespace between pressureypockets on the high pressure side of the lowpressurmwall of the vane and the-adjacent wall of the recess. The endsof the body portion 5 of the vane are provided with diagonal grooves orchannels i6 which serve to retard leakage past the ends bf the vane. Thediagonal channels IQ also receive fluid under pressure which exerts aforce on the vane toward the low pressure wall. The grooves or channelsit aid in scavenging'to the high pressure side the space between thebottom of the vane and the bottom of the slot 4 when the vane isretreating'into the'slot.

As shown in Fig. 3 of the drawings, the shoe lihas longitudinal channelsI! on the high pressure side of its working face 8 and longitudinalchannels [8 on the high pressure side of its seating face I. Thechannels I! and I8 are intersected by at least one channel l9intermediate thee'nds of the shoeanddisposed at right angles to thechannels I! and iii. The channel I9 is open to the high pressure side ofthe vane and registers with. the passage [5 of the body portion 5 of'the vane todeliver fluid under pressure to the channels it and to thebottom of the slot 4. Thegr'ooves or channels l1 and" provide the shoe,and the channel l9, which opens to the interior ofthe' pump. chamber onthe pressure side of the v'ane supplies fluid under pressure to thesegrooves or channels as well as to the passage l5v which conducts fluidunder pressure to the channel Mon the high pressure face of the bodyportion of the vane and to the bottom of The vane pr o-. vides apartition moving with the rotor to force the slot 4'.- f The shoe 6 alsohas longitudinal sealing grooves 20 on the low pressure side of theworking face 8 and. similar grooves 2| on the low pressure side of thebottom or seating face 1. One or both end faces of the shoe 6 may beprovided with transverse sealing grooves 22 to impede the-flow betweenthe end face of the shoe and the end walls of the pump chamber.

Referring to Fig. 4 of the drawings, the shoe 9 has longitudinalchannels 24 forming pressure pockets on the high pressure side of itsworking face H and longitudinal channels 25' forming pressure pockets onthe seating face I0 thereof. Channels 24 and 25 are intersected by atleast one channel '26 intermediate the ends of the shoe which extendssubstantially at right angles to the grooves or channels 24 and 25. Thechannel 26 opens to the high'pressure side of the shoe 9, and conductsfluid under pressure to the pressure pockets formed by the channels 24'and 25. The shoe 9 has longitudinal sealing grooves 2'2! onthe lowpressure side of its working face and similar sealing grooves 28 on thelow pressure side of its seating face it.

. to the pressure of the fluid being pumped at each instant of thepumping cycle.

In Figffi of the drawings, the arrows 29 and 30 r indicate the forcesapplied by thefluid under pressure to the shoes 5 and 9. The force ofthe fluid under pressure indicated by the arrows 29. is

outwardly of the center of curvature 3| otthe bottom or seating face Iof the'shoe 6 and tends.

to rotate the shoe in a direction to move the leading edge of the shoeinwardly, opposing the frictional drag exerted on the working face 8.Similarly the, fluid pressure on the shoe 9, in-' dicated bythearrows-30, is outwardly of the center of curvature 32 of the bottom orseating -face ill and tends to rotate the shoe in a direction to movethe high pressure side thereof, into the shoe recess. These forces aretransmitted tothe faces of the shoes in which the sealing grooves arelocated, as indicated by the arrows 31, 38 38 and 40, the pressure onthe shoes being commensurate' with the pressure under which the vane isworking. It should be noted that the low pressure side of the sealingshoe 6 is wedgeshaped so'that the shoe is pressed ag'ainstthe wall ofthe hbusing, as indicated by the arrows 38, and against the recess wall,as indicated by the arrows 31, so that the sealing grooves in thesespaces can effectively impede the leakage of fluid past the shoe.Similarly, the low pressure side faces in which the sealing grooves'arelocated are pressed against the rotor and the recess wall, as indicatedby the a rows 39 and 40.. v

1of the shoe 9 is wedge-shaped, so that the sur- It will be observedthat the high pressure side no ofthe recess in which the-shoes ismounted;

opens to the pump chamberrat or near theline where the'rotor 2 contactswith the wall of the housing,- so that as the shoe 8 comes into contactwith the shoe '9 the working faces of both subwardly and the highpressure side of the shoe 8 5 outwardly, a clearance is provided betweenthe opposed sharp edges of the shoes and there is no interference to thepassage in the shoe 6 past the shoe 9. b

Figure 6 of the drawings illustrates diagrammatically the forces actingupon a vane. The arrow 42 represents the direction and amount ofpressure due to the film of fluid between the face of therotorchamber'and the face of the vane. The arrow 43 represents the force dueto the working pressure against the bottom of the-vane of the fluidadmitted to the bottom of'the slot 4.

r The forces 42 and 43 are normally equal and opposed and are equalized.The arrow 44 represents the force-of a spring commensurate with 20operating conditions, such a spring being used where the speed ofrotation and delivery pressure and physical properties of fluid beingpumped are such that a force in addition to the centrif- Vugal force andthat of fluid pressure is desirable.

25 The arrow 45 represents the added force encountered when'the vane isreceding into its slot and scavenging the chamber at the bottom of theslot. This force is a valuable factor as it adds to the pressure makingthe seal at the 30 working face of the vane during a portion ofrotationin which the fluid is being compressed or delivered.

It will be noted that the vane of the present invention adds totheefliciency and capacity of the pump, since it acts as a piston pump,causing the fluid which has filled the chamber at the bottom of the slot4 during the outward movement of the vane .to be'discharged against ahigher pressure at the delivery side of the vane during the retreatingmovement of the vane.

The arrow 46 represents a force due to friction.

r The arrow 41 represents a force at the point of application due tothepressure of the load. The

at its point of application.

In the usual vane pump the force 48 is opposed by a force, indicated bythe arrow 49, at a fulcrum point formed by the edge of the slot 4 6n thelow pressure side thereof. A force, indicated by the arrow 50,. is alsoexerted. against the bottom corner of the vane on the high pressure sidethereof. The forces 48 and'50 the fulcrum point 49 tend to cant thevalue in its slot, creating localized pressures. at thepoints ofapplication of the forces 49 and 50, which are the cause of rapid wearof the. vane and slotand quick deterioration .in' efliciency ofoperation. I The present invention provides means for moreadvantageously distributing the forces acting, on

60 .the vane so as to increase the efliciency and reduce wear on thesliding parts. The arrow represents the force exerted on the vane by thefluid under pressure in the pressure pocket channels l4. -The;pres sure,indicated byAzhe arrow 65 5|, ismore than sumcient to eliminate thepressure 50 of the bottom corner of the vane against- .the highpressure-wall, and distributes the pressure of the vane over the lowpressure wall of the slot-so as to eliminate the fulcruming pressure '70indicated by the arrow. The wear is thus distributed over thesurfaces'ofthe vaneand slot arrow .48 represents the resultant of 45 and 41.

, h balanced against The arrow 53 represents the resultant of forcesindicated by the arrows 42, 43, 44 and 45 acting 1 longitudinally of thevane. The center of weight of the vane is indicated at 54 and the arrow55 represents the centrifugal force derived therefrom, and this force isalso exerted radially.

Variationsin dimensions and speed of rotationalter the force 55.The'principie of the present invention is applicable to pumps operatingat high speed or at low speed, and for pumping gases or liquids.

vane. This pump has a housing 10 and a rotor H within the housing whichcarries a sliding vane 12 mounted in a slot 13 in the rotor. The

vane'12 has a convex working face 14 which is.

provided with longitudinal. sealing grooves 16 on the low pressure facethereof and with pressure pocket channels I1 extending iongitudinally ofthe high pressure face near the bottom thereof. A passage 18 adjacentthe high pressure face of' the vane extends from the working face 14 tothe bottom of the vane and intersects each of the channels 11. The upperend of the passage 18 has a lateral opening 19 to the high pressure faceof the vane so-that fluid under pressure passes through the passage 18to each I of the pressure pocket channels 11 and to the space at thebottom of the slot between the bottom of the slot and thebottom face ofthe vane, so that, during operation of the pump, lateral pressure isapplied to the high pressure face of the vane near the bottom edgethereof, and radial pressure is also applied to the bottom face of thevane to force .the same outwardly against the wall of the pump chamber.Diagonal grooves '80 are provided on the ends of the vane to impedeleakage of fluid past the ends of the vane between the ends of the vaneand the end walls of the pump chamber, the grooves 8llalso serving toapply an additional lateral thrust to the vane andto facilitate theescape of fluid from the bottom of the-slotduring the receding movementof the vane to the high pressure side.

In some pumps it maybe desirable to modify action'of centrifugal forceupon the vane by disposing the slots, in which the'vanes slide, at anangle to the radius. If it. is desired to reduce the high frictionalresistance due to the load or speed of rotation, or both, the vane maybe placed as shown diagrammatically in, Fig. 9, with its working faceadvanced relative to the direction of rotation. The force 85representing the thrust of the fluid. being pumped in a direction'perpendicular to a radius is shown resolved'into its components, and 81,component 86 being perpendicular to the vane, and component .81 actinginwardly in a directionof movement ofthe vane. The centrifugal force at'the center of. weight 54 is shown resolved into its components 8 8 and59; component. acting perpendicular to the vane, and component" actingoutward1y.- w

The componentst'l and]! act'in' the same line but in oppositedirections.- They must be subtracted, and the resultant outward forcewhich causes frictional resistance is reduced, as 'desired, by thedegreeof the angle at which the vane is placed. Also, it is obvious that aresiiltant of forces .86- and 58 maybe found perdirection of movement ofthe vane are not 019- pendicular to the radius and that it will be lessthan the coipresponding resultant on the radial vane illustrated in Fig.6. Since this force perpendicular to the radius is a measure of thetorque, it isapparent that less power will be required to operate a:pump having its vane or vanes inclined as shown in Fig. 9.

The force 98 is added to the force 5B which holds the vane against thelow pressure wall of its recess surface to surface, due to the fact thatthe center of weight is transferred from a position on the high pressureside to a position on-the low pressure side of aradial line passingthrough the fulcrum t9.

In Fig. 10 of the drawings the angularity of the vane is the reverse ofthat'shown inFig. 9, the thrust of the fluid being pumped which isindicated by the arrow 85 being resolved into components 86*,and 81 andthe centrifugal force at thecenter of weight indicated by the arrow '55being resolved into components 88 and 89;

In this case the components 81 and 89" in the posed as in Fig. 9 but actin the same direction and their resultant is their sum instead of theirdifference.

It is to be understood that the pressure pockets at the high pressuresides of the vane and shoe and the passages for conducting fluid fromthe pump chamber to, such pockets may be formed in various ways, itbeing essential only that such pockets and passages be so disposed as tocause the fluid to exert an effective pressure against the groovedsealing faces.

' InFlg. 11 of the drawings there is shown a multi-vane pump having acasing 92 with :a cylindrical chamber 99, a rotor 96 disposedeccentrically of the chamber and having a series of vanes 95 which aremounted in slots 98 in the rotor which are disposed. at an angle toradii of the rotor. The casing and vane are provided with shoes 97 and98 which may be of the same construction as the shoes 8 and 9 previouslydescribed; 'Iheshoe 98 may be wider than the vane in which case therotor has recesses 99 at the high pressure sides of its slots toaccommodate the shoes. The vanes 95 have their inner ends tapered,providing an inclined face too which is subjected to fluidpressurewhich. acts ,to press the vane against the low pressure wall ofits slot. The inclined face 100 provides a pressure pocket on the highpressure side of'the vane which is in communication at all times withthe bottom of the slot to which fluid under pressureis conducted bychannels or passages; as in the modifications previously described.

It will be apparent that the present invention provides a simpleconstruction in which the various forces acting onthe. vanes and shoesare advantageously distributed to lessen sliding friction and wear onthe parts and to provide .an effective seal.

Furthermore, it i to be understood that the particular form of apparatusshown and de- -scribed, and the particular procedure set forth, arepresented-for purposes of explanation and illustration and that variousmodifications of said apparatus and procedure can be madewithhavingaslidingiltin out departing from my invention as defined inthe-appended claims.

What I claim is:

u i. In a pumpof the rotary piston type having relativelfrotatableelements forming walls of. the pump chamber, .anda movable sealingmember ments and provided with a face engaging the sura recess of-o'neof eleface of a relatively rotatable elementand substantially conformingto said surface to maintain a seal between high pressure and lowpressure portions of the pump chamber, said sealing member and saidrecess inwhich it is mounted being shaped to provide spaced pressurepockets be- 4 tween the member and its recess at the high pressure andunder sides of said member, said sealing member and its recess havingbearing surfaces extending the full length of said member and in slidingand sealing engagement on the low pres-. sure side thereof, said sealingmember having a passage for fluid under pressure-opening at oneend tothe pump chamber on the high pressure side of said member andcommunicating with said pockets to maintain a fluid pressure thereinsubstantially the same as in the high pressure portion of the pumpchamber to press said member against the relatively rotatable elementand against the low pressure side of its recess.

2. In a pump of the rotary piston type having relatively rotatableelements forming. walls of the pump chamber, and a movable sealingmemher having a sliding flt in a recess of one of said elements andprovided with a face engaging the surface of a relatively rotatableelement and sub- 'stantially conforming to said surface tomaintainportions of the pump chamber, said member hav ing parallelsealing grooves extending through: out its length in the face thereofwhich engages the relatively rotatable element and also in the a sealbetween high pressure and low pressure face thereof which engages thewall of the re-= I cess on thelow pressure side, said sealing member andsaid recess in which it is mounted being 'shaped to provide spacedpressure pockets bepassagefor fluid under pressure opening at one end tothe pump chamber on the high pressure side of saidmember andcommunicating with said pockets to maintain a fluid pressurethereinsubstantially the same as in the high pressure portion of thepump chamber to press said member against the relatively rotatableelement and against the low pressure side of its recess.

3. A'pump of the-rotary piston type having relatively rotatable elementsforming walls of the pump chamber, a member slidably mounted in of arelatively rotatable element and substantially conforming to saidsurface to maintain a.

- which engages the recesswallbn the high pressure side and a passagecommunicating with said a recess of one element and engaging the surfacechannels and opening to the pump chamber .on

the high pressure side of said member.

4. A pump of the rotary piston type having relatively rotatable elementsforming walls of a pump-chamber, one of said elements having a slot,aivane in said slot for maintaining a seal .between high pressure andlowpressure portions of the pump chamber, said vane comprising a bodyportion slidable in said slot and having an arcuate recess and a shoehavingan arcuate face 75 seating in said recess whereby the shoe isadapted to rock laterally in said arcuate recess, said shoe beinginterposed between the said body portion and a relatively. rotatableelement, means for applying fluid pressure to the bottom and lowpressure side of the body portion of the vane, and

means including passages formed between the arcuate face of the shoe andthe arcuate recess' in the vane for applying fluid pressure to thebottom of said shoe, and sealing grooves for impeding the flow of fluidpast said vane between 'the shoe and relatively rotatable member,between the shoe and. the low pressure side of its recess and betweenthe body portion of the vane and the low pressure side of the slot.

cl 5. A pump of the rotary piston type having relatively rotatableelements forming walls of a pump chamber, one of said elements having aY slot, a vane in said slot for maintaining a seal 20. between highpressure and low pressure portions of the pump chamber, said vanecomprising a body portion slidable in said slotand having an ,arcuaterecess and a shoe mounted to rock laterally in said arcuate recess andinterposed be- 25 tween the said body portion and a relativelyrotatableelement, the body portion of the vane having a passageextending from the arcuate recess to the bottom of the vane, the shoehavlng an arcuate bottom seated in said recess, means 30 forminga-transverse passageextending partially across the bottom of the shoefrom the high pressure side thereof andregistering with the passage inthe body portion of the vane to maintain communication between thebottomof the slot '35 and'the portion of the pump chamber immedi- "ately infront of the vane, grooves longitudinal,

with respect to the vane impeding flow of fluid between the vane and lowpressure side of its slot and between the low pressure sides of, theseat ing and working faces of the shoe and surfaces engaged thereby,pressure pockets-on the seating and working faces of the slide at thehigh pressureside which communicate with said transverse passage, and apressure pocket on the high 5 pressure side of the. body portion of thevane which communicates with the passage in the body portion of thevane. a Y

6. A pump of the rotary piston type having relatively rotatable elementsforming walls of a 5'0 pump chamber, one of said elements having a slotopening to the space between said elements,

, a vane 'slidably fitting in said'slot and having a working faceslidably-engaging the other of said elements'to'maintain a seal betweenhigh pres- 55' sure and low pressure portions of the pump 'chamber, saidvane having a plurality of parallel sealing grooves on its working face,a plurality of parallel sealing grooves on its low pressure sideinwardly of the open end of the slot and a recess.

( forming a pressure pocket on the high pressure side of the vaneinwardly of the open end of the slot, anda passage in said vane openingto the high pressure side thereof adjacent the working face, saidpassage'extending'to the bottom of the pocket, Y I l v 3 'l. A pump of,the rotary piston type having relatively'rotatable elementsforming wallsof a 70 pump chamber, one ofsaid elements having a slot,

'a' vane in said slot for maintaining a seal between high pressure andlow-pressure portions .of the pump chamber, said vane having sealinggrooves on its working face" and itslow pressure- 75 side, diagonalgrooves. on its end faces, pressure the high pressure side of the anarcuate working vane and communicating with said pressure pockets on itshigh pressure side, and a passage communicating with said pockets andopening to vane-adjacent its working face. I

'8. In a-pump of the character described, relatively rotatable elementsforming walls of a pump chamber, one of said elements having an arcuatesurface, the other of said elements having an arcuate recess with aradius of curvature less than that of said surfac'e,. a sealing shoehaving an arcuate seating face fltting in said recess and an arcuateworking face which conforms to said arcuate surface to provide a sealbetween high and low pressure portions of the pump chamber, each of.said arcuate faces of the shoe having a transverse channel extendingfrom the high pressure side thereof partially across said face, andlongitudinal grooves in said faces intersecting said channels andforming pressure pobkets on the working and seating faces'of the shoeadjacent the high pressure side thereof.

9. In a pump of the character described, relatively rotatable elementsforming walls of a pump chamber, one of said elements having an arcuate.surface, the other of said elements having an arcuate recess with aradius of curvature less than that of said surface, a sealing shoehaving an arcuate seating face fitting in said recess and 'an arcuateworking face which conforms to said arcuate-surface to provide a sealbetween high and low pressure portions of the pump chamber, each of saidarcuate faces of the shoe having a transber and the other being ofsmaller diameter and forming the cylindrical inner wall of the chamberand tangentially disposed with respect to the outer wall, a vane carriedby one element and comprising a slidably mounted body portion pro-\vided with an arcuate recess and a shoe having an arcuate face'of acurvature corresponding to that of the recess and "seating in saidrecess and face of the. same curvature as the relatively rotatableelement, an arcuate recess in the other element and an arcuate shoe in'said recess-having a seating face conforming to said recess and aworking face conforming to the surface'of the rotating element,thearcuate seating face ofsaid last named shoe being slidable in thearcuate recess in a direction trans- I versely of the axis of theseating faceand adapt- 1 ed to turn aboutthe axis of its seating face,and

means for applying fluid pressure, to arcuate faces of said'shoes indirections tending to ro-. tateeach shoe on its seat in a direction'torelieve on the.r otating element approaches the shoe on the stationaryelement.

11. A rotary piston pump having relatively rotatable, 'eccentricallydisposed elements, one

- the pressure on the working face adjacent the w highpressure side'ofthe shoe whereby the 6pposed edges of the shoes are retracted asthe shoeand forming the cylindrical inner wall of the chamber and tangentiallydisposed with respect to the outer wall, a vane carriedby one elementand comprising a slidably mounted body portion provided with an arcuaterecess and a shoe having an arcuate face of a curvature corresponding tothat of the recess and seating in said recess and an arcuate workingface of the same curvature as the relatively rotatableelement, anarcuate recess in the'other element and an armate shoe in said recesshaving a seating face conforming to said recess and a working faceconforming to the surface of the rotating element, each shoe havingpressure pockets adjacent its high pressure edge adapted to receivefluid under pressure which tends to rotate the shoe about the center 01curvature of its seating face.

12. A rotary piston pump having relatively rotatable, eccentricallydisposed elements, one

forming the cylindrical outer wall of the pump chamber and the otherbeing of smaller diameter and forming the cylindrical inner wall of thechamber and tangentially disposed with respect to the enter wall, one ofsaid elements having a slot, a vane slidably mounted in the slotandengaging the relatively rotatable element, said vane having a passageopening at one end at the high pressure side of the vane to the pumpchamber and at the other end to the bottom of said slot whereby saidvane acts as a piston pump during a relative rotation of said elements,said vane having grooves on its end faces which extend diagonallynfromthe bottom to the high pressure side of the \vane to impede flow towardthe low pressure side and to conduct fluid to the high pressure side ofthe vane.

ROBERT DEMING.

